The biomechanical parameters underlying reconstruction of the anterior cruciate ligament (ACL) of the knee have been incompletely studied. The ACL is frequently totally discrupted in athletic trauma and other accidents. Since the ACL is important in the kinematics of the knee, its correct function is vital in maintaining joint integrity. We will utilize a proven Hall-effect displacement transducer to measure ligament strain prior to and immediately following ligament reconstruction in canines. The same technique will be used as part of the measure of function after two year's rehabilitation. At two years we will also measure the strength of the ligament at the time of sacrifice. We will relate a composite score of function and joint pathology to the biomechanical quality of the original reconstruction. The functional score of the reconstructed and control groups will be compared. Thus, we will establish the importance of the orgiginal strain pattern of the ACL as well as clarifying the ability of the reconstruction to mimic the biomechanical functions of the ACL. In a related study, the protective function of casts, cast braces and other braces commonly used following ACL reconstructions will be compared in human cadavers using the Hall effect device. Similation of appropriate motion and muscle function (isometric in totally restrictive devices such as casts and locked braces and limited isotonic activity in partially mobile braces and cast braces) while measuring the ACL strain should allow clarification of the safest means of rehabilitation of the knee.